Research On Reservoir Physical Properties And Influencing Factors Of Chang 6 Oil Layer Group In Area L Of Nanniwan Oilfield

Area L of the study area is located in the southeastern part of the Ordos Basin.The Chang6 oil layer group of the Triassic Yanchang Formation is the main development strata in the study area.Based on basic geological data,well logging data,geological logging data,and physical property analysis data,this paper analyzes the main development of sedimentary microfacies,sand body plane distribution,diagenesis,and reservoir physical properties in the study area,and establishes a reservoir physical property interpretation model.And analyze the main influence factors of reservoir physical properties.The Chang 6 oil layer group in the L area develops delta front subfacies,mainly developing underwater distributary channels,underwater distributary channel flanks,and interdistributive bay microfacies.he lithology is dominated by fine-grained feldspar sandstone,and the diagenesis has compaction,cementation,dissolution and chlorite clay film inhibition.The pore types mainly include intergranular dissolved pores,intragranular dissolved pores,residual intergranular pores and mold pores.Chang 6 reservoir has an average porosity of 10.2% and an average permeability of 0.68×10-3?m2,which belongs to IIIb-IVa reservoirs.On the basis of core homing,using the relationship between porosity and sonic time difference curve(DT),a unitary regression method is used to establish a porosity interpretation model,and the correlation coefficient R=0.908.Based on the logging parameters in the porosity interpretation model,a ternary regression equation was established using acoustic time difference,natural gamma,spontaneous potential and permeability,with a correlation coefficient R=0.810.The measured porosity and permeability data are superimposed with the sand thickness map.The high values of porosity and permeability data are generally distributed in the underwater distributary channel,and the low values are mainly distributed in the flanks of the underwater distributary channel,and some have high values.The distribution of the measured average porosity in the subgroup is Chang 61(11.47)> Chang 63(10.63)> Chang 62(9.86)> Chang 64(9.67).The average measured permeability in the subgroup is Chang 61(0.71).>Chang 63(0.69)> Chang 62(0.66)> Chang 64(0.54).The main controlling factors of reservoir physical properties in the study area are sedimentation and diagenesis.In sedimentation,there is a linear relationship between the quartz content of the clastic component and the porosity.The correlation coefficient with porosity is R= 0.447,and the correlation coefficient with permeability is R = 0.04.There is no obvious correlation between the two.There is no correlation between the change of average particle size and the correlation coefficient of porosity and permeability R<0.1.Except for the factor of particle size,the sorting and homogeneity of the rock affect the physical properties of the reservoir.Under the control of sedimentary microfacies,the underwater distributary channel is located in the strongest hydrodynamic environment,followed by the flanks of the underwater distributary channel,and the diversion bay is located in the smallest hydrodynamic environment.The average porosity of the underwater distributary channel is 10.6%,the average permeability is 0.62×10-3?m2,the average porosity of the distributary channel flanks is 8.7%,the average permeability is 0.51×10-3?m2,the distributary channel porosity is 7.1%,and the permeability is 0.43×10-3?m2.The physical properties of the underwater distributary channel are better than the flanks of the underwater distributary channel,and the inter-distributary bay is relatively the worst.The impact of diagenesis on the physical properties of this area is mainly manifested as compaction,cementation and dissolution.The study area generally develops argillaceous cementation,feldspar dissolution,and mica is compressed and deformed.